/usr/include/OGRE/Plugins/OctreeZone/ is in libogre-dev 1.7.4-3.
This file is owned by root:root, with mode 0o755.
..
/usr/include/OGRE/Plugins/OctreeZone/OgreHeightmapTerrainZonePageSource.h
/usr/include/OGRE/Plugins/OctreeZone/OgreOctreeZone.h
/usr/include/OGRE/Plugins/OctreeZone/OgreOctreeZoneOctree.h
/usr/include/OGRE/Plugins/OctreeZone/OgreOctreeZonePlugin.h
/usr/include/OGRE/Plugins/OctreeZone/OgreOctreeZonePrerequisites.h
/usr/include/OGRE/Plugins/OctreeZone/OgreTerrainVertexProgram.h
/usr/include/OGRE/Plugins/OctreeZone/OgreTerrainZone.h
/usr/include/OGRE/Plugins/OctreeZone/OgreTerrainZonePage.h
/usr/include/OGRE/Plugins/OctreeZone/OgreTerrainZonePageSource.h
/usr/include/OGRE/Plugins/OctreeZone/OgreTerrainZonePrerequisites.h
/usr/include/OGRE/Plugins/OctreeZone/OgreTerrainZoneRenderable.h